The present invention relates to pre-distortion in transmitter circuits. In particular, the invention relates to the use and control of pre-cursor, cursor and post-cursor signals in a high data rate transmitter.
High speed data transfer between semiconductor devices in an electronic system may be achieved by the use of a serialiser/deserialiser (SerDes). In order to avoid the use of a plurality of parallel connections between devices, a single differential analogue path is used running at a high data rate. One exemplary arrangement is specified by IEEE 802.3/AE/P.
It is well known to provide pre-distortion to signals for transmission in an attempt to cancel out the distortion that will be introduced into the signal by the transmission channel.
By way of example, FIG. 6a shows a simple square wave that it to be transmitted over a channel. FIG. 6b shows that signal after is has been subjected to pre-distortion in an attempt to compensate for the impact of the channel on the signal.
The signal in FIG. 6b includes a negative pre-cursor element (indicated by the reference numeral 600), a large cursor element (indicated by the reference numeral 602) and a post cursor element (indicated by the reference numeral 604) between the level of the pre-cursor and the cursor. As shown in FIG. 6b, the pre-cursor element 600 is transmitted before the cursor element and the post-cursor element 604 is transmitted after the cursor element.